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在ESR测年研究中,被测样品的年代是通过样品的古剂量与样品所接受的年剂量的比值得到的。古剂量则是在实验室内经放射性源的人工辐照模拟自然界的ESR信号增长情况获得的。因此,人工辐照样品吸收剂量的确定成为影响测年可靠性的一个重要因素。目前一般有两种方法确定测年样品的人工辐照吸收剂量值一种是剂量率法,即在辐照前利用标准剂量体系对辐照位置的吸收剂量率进行校准,然后在同一位置辐照被测样品,通过校准得到的吸收剂量率和辐照时间确定样品的吸收剂量,通常所用的标准剂量体系为硫酸亚铁剂量计;另一种是伴随法,即在辐照前将参考剂量计与被测样品一起放到辐射场中辐照,参考剂量计一般采用经标准剂量体系(如硫酸亚铁剂量计或量热计等)校准过的丙氨酸剂量计,照后由参考剂量计直接给出被测样品的吸收剂量。文中就确定吸收剂量的两种方法的可靠性进行了探讨,并利用两种类型的丙氨酸剂量计通过伴随法测定了被测样品的吸收剂量。结果表明,根据目前ESR测年研究中地质样品人工辐照的实际情况,利用伴随法通过参考剂量计确定被测样品的吸收剂量更为实用与可靠。
In the ESR dating study, the age of the sample to be measured is obtained from the ratio of the ancient dose of the sample to the annual dose of the sample. The ancient dose was derived from simulated growth of ESR signals in nature by artificial sources of radioactive sources in the laboratory. Therefore, the determination of absorbed dose of artificial irradiation samples becomes an important factor affecting the reliability of dating. There are currently two general methods of determining the absorbed dose of artificial radiation for a dating sample. One is the dose rate method, which uses a standard dose system to calibrate the absorbed dose rate at the irradiation site prior to irradiation and then irradiates at the same location The sample to be tested, the absorption dose rate and the irradiation time obtained by the calibration to determine the absorbed dose of the sample, the standard dosage system commonly used is a ferrous sulfate dosimeter; the other is a concomitant method, ie before irradiation, a reference dosimeter Together with the sample to be tested in a radiation field. The reference dosimeter generally uses an alanine dosimeter calibrated with a standard dosage system (such as a ferrous sulfate dosimeter or a calorimeter, etc.), and a reference dosimeter Directly given the measured sample absorption dose. The reliability of the two methods for determining the absorbed dose was discussed in this paper. The absorbed dose of the tested sample was determined by the concomitant method using two types of alanine dosimeters. The results show that according to the actual situation of artificial irradiation of geologic samples in ESR dating, it is more practical and reliable to use the adjoint method to determine the absorbed dose of the tested sample by reference dosimeter.